This invention relates to polyesterimide polymers, processes for preparing the same and articles containing the same. More particularly, this invention is directed to polyesterimide compositions and processes for preparing the same, and to such compositions which can be applied either in a solvent or solventless process as a magnet wire coating with the resulting magnet wire exhibiting excellent flexibility, heat shock, dielectric, and thermal properties.
In the manufacture of magnet wire, that is, an electrical conductor with an insulating enamel coating which should possess desirable properties such as electrical insulating properties, resistance to heat and solvent attacks and the like, the insulating enamel is normally applied with conventional equipment in a solvent based system in which the enamel is dissolved therein for ease of application to the wire. Such solvent based enameling systems have many and various disadvantages among which are included the cost of the solvent, manufacturing pollution caused by the solvent and the like. Most enamels of the polyestermimide types, however, are synthesized in a solvent in order to achieve sufficient molecular weight which allows the final synthesized polymer to be used directly in the solvent based enameling system with further dilution, if necessary.
As can be appreciated therefore, a polyesterimide composition which can be prepared without the use of solvents and used in a hot melt condition in conventional equipment and with conventional techniques as a magnet wire coating would represent an advancement in or a contribution to this art. Such would be particularly advantageous of the resulting magnet wire exhibits excellent flexibility, heat shock, dielectric, and thermal properties. Equally advantageous would be a polyesterimide composition which would be applied either in a hot melt condition or in a solvent based system in order to permit processing flexibility.